Dilated cardiomyopathy is the most common form of heart muscle disease. Although it is found most often in middle-aged people and more often in men than in women, this condition has been diagnosed in people of all ages, including children.

Also called "congestive cardiomyopathy," dilated cardiomyopathy damages the muscle tissue that makes up the heart's pumping chambers. If the chamber walls become weak enough, the heart can no longer perform its normal pumping action.

At first, your body's functions will remain near normal. Other parts of the body will try to make up for the heart's decreased pumping power by increasing the amount of fluid they hold—and by making more blood than usual. The heart chambers then expand (dilate) to make room for this greater blood volume. This expansion can initially restore some of the heart's pumping strength because the more a muscle is stretched, the more forcefully it can contract.

But, in time, the stretching of the heart muscle causes the heart to get bigger, or enlarge. This is called cardiomegaly. Doctors can usually tell if cardiomegaly is present by measuring the size of your heart. Cardiomegaly is present if the diameter of the heart is more than 50% of the inner diameter of the ribcage (the cardiothoracic ratio).

The long-term effects of cardiomegaly are not good. Your heart will try to increase its rate to pump more blood through your body. And, when the heart cannot contract as well, it will affect your circulation and cause excess body fluid to build up in your lungs, the area above your stomach (abdomen), and your legs. This fluid buildup makes breathing difficult and causes swelling (called edema). These are 2 common symptoms of heart failure.

Cardiomegaly sometimes leads to abnormal heart rhythms (called arrhythmias). Also, blood flows more slowly through an enlarged heart, so blood clots may easily form. These clots can break free and enter the circulation, ending up in the lungs (called a pulmonary emboli) or blocking a vessel in the brain or heart.

What are the causes?

Most cases of dilated cardiomyopathy are called "idiopathic," which means that no exact cause can be found. Some doctors think that viral infections may be responsible. Because you may have had the viral infection months or even years before you show any sign of a weakened heart muscle, the exact cause of dilated cardiomyopathy is difficult to pinpoint.

Other cases of dilated cardiomyopathy can be traced to the following causes:

Alcohol and other toxic substances

Up to 30% of cases of dilated cardiomyopathy can be linked to heavy drinking. After years of heavy drinking, the heart can be weakened by alcohol's toxic effect on its muscle cells. Also, heavy drinkers tend to drink alcohol instead of eating food, which leads to poor nutrition. Other toxic substances, including some chemicals and pesticides, have also been shown to weaken the heart muscle. Also, drug abuse has been found to weaken the heart muscle.

Poor nutrition

If your body does not get enough of the essential vitamins and minerals it needs, especially vitamin B-1, it can lead to dilated cardiomyopathy. This is more common in developing countries than in the United States and other developed nations.

Inflammation

In a rare condition called myocarditis, the heart muscle becomes swollen or inflamed because of an infection by a virus, less often, by bacteria, or by another infective process. You may not feel any symptoms at all. You may have an achy feeling in your chest and feel tired like you have a bad cold or the flu. Usually, a mild case of myocarditis will go away without any lasting damage. In fact, you may not even know you have it. Severe cases are often not diagnosed until you have the symptoms of heart failure. Even a severe case may go away without notice, but these severe cases usually cause ongoing heart muscle damage that cannot be reversed.

Pregnancy and childbirth

In rare cases, women may develop heart muscle disease late in pregnancy or during the first few months after child birth. This is called peripartum cardiomyopathy. With or without having had a viral or bacterial infection, a pregnant woman's heart muscle may become inflamed. Researchers do not know why this happens. They do know that if the woman gets over the disease and becomes pregnant again, she is again at risk for developing the condition. Also, in the United States, African American women develop peripartum cardiomyopathy more often than women of other races do.

Heredity

Although scientists do not know if there is a gene that causes people to develop dilated cardiomyopathy, many think that genetics plays a role. They point to cases where members of the same family have the disease. Also, some genetic brain disorders, such as muscular dystrophy, are associated with heart muscle disease.

Acquired immune deficiency syndrome (AIDS)

Recent studies have shown that AIDS increases the risk of dilated cardiomyopathy. Anywhere from 1% to 8% of patients with AIDS have this type of heart damage.

What are the symptoms?

Sometimes dilated cardiomyopathy does not cause any symptoms. At other times, you may feel symptoms most often associated with the common cold or flu: chills, fever, overall aches, and fatigue.

When your heart becomes very enlarged, you will feel symptoms. These symptoms include chest pain, extreme tiredness, shortness of breath, and swelling of the legs and ankles. All of these are the early signs of heart failure.

How is it diagnosed?

A chest X-ray will show if your heart is enlarged and if there is fluid in your lungs.

Echocardiography can be used to show the size of your heart and how much damage there is. Echocardiography is also used to see if there is decreased heart wall motion (called hypokinesia or hypokinesis).

Angiography, a cardiac catheterization procedure, can give a detailed view of how well your heart's arteries, chambers, and valves are working.

A biopsy of tissue from the wall of your heart may help doctors find out how seriously your heart has been damaged, or what process may be causing the damage.

How is it treated?

Whether a cause can be identified or not, treatment focuses on relieving the symptoms, as well as on relieving the extra load on the heart. Lifestyle changes, medicines, and surgery may be needed.

If doctors can find the cause of your dilated cardiomyopathy, your treatment may be more specific. For example, changing what you eat or limiting how much alcohol you drink can actually reverse the damage that has been done to your heart. In some cases of alcohol-caused dilated cardiomyopathy, quitting drinking altogether allows your body to repair itself.

Lifestyle changes

Some people may need to lose weight and stop smoking. You should also try to get enough sleep, limit how much salt you eat, and start a moderate exercise program that has been approved by your doctor. Improving your overall fitness can help ease the demands on your heart and help your medicines work better.

In some cases, patients may need to have oxygen available at all times.

Surgery

For some patients, the damage to the heart muscle is so bad that medicines are not enough. For these patients, doctors may recommend a heart transplant. Patients may need the support of a heart assist device while they are waiting for a donor heart. In some cases, the device may give the heart enough time to recover its function so that the patient no longer needs a heart transplant.